1. Field of the Invention
The invention is directed to a stalk roll having a revolving cornstalk engagement gap for a corn header.
2. Description of the Prior Art
In the past thirty years, four external factors have greatly impacted corn harvesting. First, environmentally friendly residue management rules mandate that the farmer keep a certain percentage of crop residue on the surface of the land to prevent soil erosion. Second, yields have doubled through improved genetics, fertilization, populations, and row spacing. Third, genetics have also improved plant health and stalk vigor. Fourth, harvesting machines are larger with increased horsepower, capacity, ground speed, and the machines utilize corn heads with more row units.
In combination, these factors require that during separation of a corn plant ear (or “ear”) from a cornstalk (or “stalk”), modern stalk rolls: (1) increase the rate of ear separation; (2) ensure that the corn plant is not severed from its root system; (3) increase the speed at which cornstalks are ejected from the row unit; (4) retain minimal amounts of material other than ears (“MOTE”) in the heterogeneous material being delivered to the combine for threshing; and, (5) lacerate and/or penetrate the shell of the stalk to expose the internal portions of the stalk for accelerated decomposition of the stalk.
As shown in FIG. 1, modern corn headers are provided with several row crop dividers (snouts) for retrieving, lifting, and directing the rows of cornstalks toward their respective corn plant engagement chambers. The corn plant engagement chamber is defined herein as the portion of the corn head row unit that engages the cornstalk and separates the ear from the corn plant. FIG. 1A shows the top view of two stalk rolls found in the prior art. Gathering chains located in the corn plant engagement chamber draw the stalks towards the header. Stalk rolls located beneath the gathering chains pull the stalks rapidly downward, returning the stalk to the field. These stalk rolls are powered by a gearbox. As the stalk rolls rotate, the flutes on the stalk rolls engage and pull the cornstalks downward. Two stripper plates located above the stalk rolls, with one stripper plate on either side of the corn row, are spaced wide enough to allow the cornstalks and leaves to pass between them but narrow enough to retain the ears. This causes the ears to be separated from the corn plant as the cornstalk is pulled down through the stripper plates. The stalk rolls continue to rotate and eject the unwanted portions of the corn plant below the corn plant engagement chamber, thereby returning the unwanted portions of the corn plant to the field.
The performance of stalk rolls found in the prior art, as shown in FIGS. 3-5, has been found to be less than optimal. Attempts at increasing stalk roll performance and increasing ear separation speed have been made by increasing rotational speed of the stalk rolls. This was unsuccessful because stalk rolls having uniform length flutes rotating at high speeds simulate a solid rotating cylinder, which restricts entry of the corn plant into the corn plant engagement chamber. The diameter of the simulated rotating cylinder is approximately equal to the distance from the tip of a first flute on a given stalk roll to the tip of a second flute oriented closest to 180 degrees from the first flute. This rotating cylinder effect prevents individual flutes from engaging the cornstalk and restricts corn plants from entering the corn plant engagement chamber. Thus, cornstalk engagement is hindered and the corn plant hesitates and does not enter the corn plant engagement chamber.
The prior art has attempted to increase the performance of cutting or chopping stalk rolls by adding more flutes to the stalk rolls. In effect, this reduces the performance of the stalk rolls because during rotation of the stalk rolls, a semi-continuous wall of steel that restricts entry of the cornstalk into the corn plant engagement chamber, as noted above. As more flutes are added to the stalk roll, rotation of the stalk roll causes the stalk roll to more closely simulate a rotating cylinder. When viewed along the axis of rotation of the stalk roll (the direction from which the stalk rolls would approach the cornstalk), adding more flutes restricts the ability of the cornstalks to enter the corn plant engagement chamber due to interference from the ends of the flutes. The result from higher rotational speeds of the stalk rolls explained above, or from an increased number of flutes is sometimes referred to as an eggbeater effect. When the gathering chain paddle passes above the stripper plates and engages a corn plant that is restricted from entering the corn plant engagement chamber, it will break or sever the cornstalk prior to ear separation. Cornstalk severance prior to ear separation increases intake of MOTE to the combine, thereby increasing horsepower and fuel requirements. This hesitation may also cause ear separation to take place near the opening of the row unit and allow loose ears to tumble to the ground, thereby becoming irretrievable. (See U.S. patent application Ser. No. 10/376,657 filed by applicant.)
FIG. 3 shows prior art opposing stalk roll designs utilizing six flutes that inter-mesh and overlap. When the flutes of this type of stalk roll engage the cornstalk, the flutes alternately apply opposing force. This knife edge relationship causes at least two problems. First, the corn plants are violently tossed from side to side causing premature separation of loosely attached ears, thereby permitting the ear to fall to the ground and become irretrievable. Second, the cornstalk is cut or snapped at a node causing long, unwanted portions of the cornstalk and leaves to stay attached to the ear and remain in the row unit. This eventually creates a pile of trash or fluff in front of the cross-auger and feeder house and increases the amount of MOTE the combine must process. This problem is compounded as the number of row units per corn head is increased.
FIG. 4 shows the prior art stalk roll design with intermeshing knife edges as described in U.S. Pat. No. 5,404,699. As shown, the stalk rolls have six outwardly extending integral flutes. Each flute has a knife edge that is provided with a leading surface and a trailing surface. A respective knife edge extends the length of each flute in the direction radially distal from the stalk roll. The leading surface of the knife edge has a ten degree forward (with respect to the rotation of the stalk roll) slope and the trailing surface has a thirty degree reverse slope (with respect to the rotation of the stalk roll), both of which slopes are defined with respect to a radial plane extending through the vertex of the knife edge and the central longitudinal axis of the stalk roll. Therefore, the leading surface is steeper than the trailing surface of each knife edge. The radially extending flutes of the stalk rolls located in the corn plant engagement chamber are interleaved with one another in an intermeshing-type arrangement. The stalk rolls may be mounted in a cantilevered arrangement; or alternatively, in an arrangement employing nose bearings. The stalk roll comprises a cylindrical shell formed by two semi-cylindrical pieces that are clamped about a drive shaft. Bolts extend between the two semi-cylindrical pieces to pull the pieces together, thereby clamping the stalk rolls to the drive shaft.
This design, upon restricted engagement of the stalk roll with the cornstalk, allows the knife edges to cut stalks before pulling the stalks through the stripper plates to separate the ear from the stalk, effectively leaving the upper portion of the corn plant free to float in the corn row unit as shown in FIG. 3. This requires the combine threshing components to process a substantial portion of the stalk; again increasing combine horsepower and fuel requirements.
U.S. Pat. Nos. 4,845,930 and 5,040,361 disclose stalk rolls having interleaved canted blades for chopping the cornstalks (not shown). U.S. Pat. No. 4,233,804 discloses a stalk roll having six flutes in which three of the flutes are radially aligned with the central longitudinal axis of the stalk roll (not shown). Other chopping stalk rolls are disclosed in U.S. Pat. Nos. 3,304,702 and 4,974,402 (not shown). Semi-cylindrical husking rolls have been clamped onto drive shafts by bolts as disclosed in U.S. Pat. Nos. 2,469,687, 2,538,965, and 3,101,720 (not shown).
FIG. 5 shows the design disclosed by U.S. Pat. No. 6,216,428, which is a stalk roll having bilaterally symmetric flutes with knife edges which are adjacent and overlap in the shear zone area. This design produces a shearing and cutting of the cornstalk using a scissor configuration produced by the leading and trailing edges of the opposing knife-edged flutes. Again, the cornstalks are cut off prior to ear separation. This is sometimes referred to as a scissor effect and also results in the need to process increased amounts of MOTE. As disclosed, the flutes of the stalk roll are detachable. The stalk roll of U.S. Pat. No. 6,216,428 is designed for use on Case New Holland corn heads that do not require nose bearings at the entrance (of corn plants) to the stalk rolls to operate properly and are mounted in a cantilevered arrangement.
Case IH corn heads built prior to development of U.S. Pat. No. 6,216,428 used stalk rolls having four knives that are bolted to a solid shaft. Adjacent stalk rolls are registered with one another so that as the stalk rolls are rotated, the knives of the opposing stalk rolls are also opposing rather than intermeshing. In an opposing arrangement, the knives come into contact with opposite sides of the cornstalk at the same general height of the cornstalk, thereby lacerating the cornstalk for accelerated decomposition. It is important that the blades are correctly registered with one another, and that the blades are correctly spaced from one another. The stalk rolls used on Case IH corn heads require nose bearings at the forward end (with respect to the direction of travel of the combine during threshing) of the stalk rolls to operate properly and may not be mounted in a cantilevered arrangement.
The stated objective of the prior art disclosed in FIGS. 4 and 5 is to promote faster decomposition of the crop residue, increased erosion control, and decreased plugging of tillage tools. However, a finely cut cornstalk that is severed from the ground may actually reduce the erosion protection provided by crop residue because it washes or blows from the field, leaving the soil particles susceptible to erosion due to rain or wind. This type of crop residue management system has now been determined to be environmentally unfriendly.